The objective of this experiment is to design, produce, implant and evaluate a segmental, porous replamineform prosthetic implant for long bones. The proposed implants will be stainless steel and fabricated into two basic configurations. One will take the form of a porous coated intramedullary rod with adjustable porous coated rings to serve as spacers between the resected bone ends. The other will be a porous coated segment similar in diameter to the resected bone with smaller flanges at each end to fit into the medullary cavity of the resected bone ends. Although experiments involving implants similar to the second design have been carried out by other researchers, none have been performed in which the porous configuration was produced by the replamineform process. The replamineform process is a technique which permits the replication of certain naturally occurring porous microstructures seen in coral genera. Porous implants produced by this technique have: 1. uniformity of pore size throughout the implant, 2. complete interconnection of pores, 3. a relatively high strength to weight ration, and 4. reproducibility of a pore size within the recommended range for bone ingrowth. Other methods using sacrificial spheres and fiber metal composites have been described for porous implant manufacture, but none of these has been able to consistently produce this useful combination of structural characteristics. Experiments in this laboratory have demonstrated that good bony ingrowth and firm skeletal attachment can be obtained in replamineform alumina cylinders implanted in bone. This project will evaluate the first utilization of this porous configuration in an environment with physiologic stresses and loading. It remains to be seen whether under these conditions good bony ingrowth and permanent, firm skeletal fixation of the prosthesis will take place. If this occurs, the way may be opened for the eventual clinical use of such a prosthesis.